condition mean min max ZT0-3 5.472465 5.472465 5.472465 ZT4-7 5.55505 5.55505 5.55505 ZT8-11 4.746589999999999 4.746589999999999 4.746589999999999 ZT12-15 5.671234999999999 5.671234999999999 5.671234999999999 ZT16-19 5.6739049999999995 5.6739049999999995 5.6739049999999995 ZT20-23 5.278325 5.278325 5.278325